Author Topic: Broken Tap- Need Help (Read 7870 times)

WKevinD · « **on:** May 22, 2014, 12:14:34 AM »

I just broke a tap, not the first time but the first time I can't get a hold on it.
I was trying to tap the front lockbolt hole with a 6/32 (thin web- thought I'd outsmart it !) and the tap snapped, I was going slow and backing out the cuttings, using tapping oil and being ever so gentle, well obviously not careful enough.
The tap snapped flush with the inside and outside of the plate. I can step up to a 8/32 and notch the bottom of the barrel or taper the new bolt if I can get the tap out. Can the tap be annealed in place? How?
Any other suggestions would be appreciated.

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flehto · « **Reply #1 on:** May 22, 2014, 12:35:37 AM »

If you live near a tool and die shop, they can EDM it out and save the hole . Whether you can anneal the tap depends on the tap metal...if it's HSS , forget the annealing. A carbon steel tap could be annealed......Fred

Acer Saccharum · « **Reply #2 on:** May 22, 2014, 01:13:47 AM »

What Fred said.

Dan Fruth · « **Reply #3 on:** May 22, 2014, 01:15:18 AM »

A broken tap can be removed, but somrtime it needs to go to the edm or a hole popper. Try taking a center punch and trying to unscrew the tap by driving the punch into a corner of the broken stub. If you have one, you can drill a tap with a carbide drill, but that is done in a mill. You can also sometime break the tap and dig out the pieces with a dental pick...If all else fails, try to drive it out, which will destroy the hole, but that can be fixed as well.

Stophel · « **Reply #4 on:** May 22, 2014, 01:40:26 AM »

So, you just barely got the tap started before it popped???

Anyway, if it's a regular carbon steel tap, just pound it out. Take a punch sized so it can fit in the "through hole" but smaller than the threads and break that sucker out. It's scary, I know, but you'll be surprised how easy it is to simply drive it out, snapping the threads right off the tap. AND, the threads in the lockplate may even be just fine.

Through holes are easy. If it was a blind hole.....

With those I have had to just heat and anneal it and drill it out. Not fun, but still doable.

Oh, and what drill bit did you drill your hole with? If it is even one size too small, you're almost guaranteed a broken tap.

David Rase · « **Reply #5 on:** May 22, 2014, 01:52:57 AM »

I snapped off a carbon steel tap in a flintlock cock once while tapping the threads for the top jaw screw. Prior to slowly heating up the piece with the broken tap to cherry red, I heated up a 1' x 1/8" piece of steel and stuck in in my container of wood ashes. Once the part was red, I removed the steel bar and placed the cock and tap into the preheated ashes. It took a little more than 2 hours to cool down. Once cool, I was able to center punch the annealed tap and drill out the center with a drill that just touched the cock threads. After drilling I used a pick to remove the tap pieces. The broken tap came out in rings. I chased the threads with a new "sharp" tap and continues on with he project.
David

jerrywh · « **Reply #6 on:** May 22, 2014, 02:16:14 AM »

Like Dave said , if it is a carbon tap you can anneal it but it probably is high speed steel as most taps are now. You will not be able to anneal a high speed tap without hurting the lock plate. If you have some nitric acid put a drop in the hole and wait for an hour. It might take two or three applications but it will loosen the tap eventually. If that doesn’t/t work just drive it out backwards with a hammer and punch. EDM's are great but you might not find one and it won't be free.

44-henry · « **Reply #7 on:** May 22, 2014, 03:10:25 AM »

You might be able to cut a slot in the end on the inside of the plate with a dremel tool with a cutting disk. You will probably cut a notch in the plate, but that can always be filled later if necessary. With a slot you should be able to back it out with a screwdriver.

WKevinD · « **Reply #8 on:** May 22, 2014, 04:05:14 AM »

Thanks guys, don't have a clue what an EDM is but I'll ask around.
The tap was an Irwin "high carbon steel bottom tap" 6-32, the hole was drilled with a #36 drill.
I was tapping from the stock side with a clearance hole (for an 8-32)
So far I've tried breaking with a center punch but just flattened the point, I tried pushing it counterclockwise
but a 6-32 is darn small and there is no spot to "bite" and spin.
I knew it was a potential broken tap but usually there is enough of a stub to grab and turn. I figured if it screwed up I could back it out and #1 try again, #2 use the 8-32 I was avoiding. So much for figuring.
I hate felling like a dumb a**

WKevinD · « **Reply #9 on:** May 22, 2014, 04:12:23 AM »

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This is the inside view of the lockplate

PPatch · « **Reply #10 on:** May 22, 2014, 04:16:50 AM »

Don't go feeling like a DA, its normal stuff and where do you think all the experienced answers are coming from... We've all been there one way or another.

dp

Stophel · « **Reply #11 on:** May 22, 2014, 04:58:31 AM »

You need to drive it back out the way it went in.

And don't be afraid to hit it hard. You'll need a good, stiff pin punch made out of hardened spring wire or something like that. A soft punch will just bend over and make a mess.

Further, since this is a through hole, you will find it MUCH better to use a normal taper tap. The bottoming tap was wanting to cut too much, too soon. Bottoming taps are only good for blind holes, and I HATE doing them.

WKevinD · « **Reply #12 on:** May 22, 2014, 05:06:30 AM »

Quote from: Stophel on May 22, 2014, 04:58:31 AM

You need to drive it back out the way it went in. And don't be afraid to hit it hard.

Thanks, that's the plan for tomorrow AM, hopefully I can shatter the tap and dig it out. I'll have to find a good punch first.

I'll let you know how I make out.

docone · « **Reply #13 on:** May 22, 2014, 05:23:49 AM »

A dremel, and a diamond point. Being high speed steel, it will dull a lot of stuff.
Grind off one of the flutes, then try to back it out. If that does not work, cut off another one.
You will need to run the Dremel at higth speed, and use lots of lube, or the diamond point will not last long. Easy pressure also.
I snapped one off in an 03-A3 reciever once. That is how I got it out, but it was nasty.
Good luck with it. Should come out fast.

Dave B · « **Reply #14 on:** May 22, 2014, 06:45:00 AM »

I picked up a tap extractor for a three fluted tap to bail my self out of the exact situation. I have used it on a number of broken taps. I am not sure where it went since we moved. I think mine was for a 8-32 though. They may make one for a 6-32. It works by three fine steel wires held in place by a fluted shaft with a sliding collar. the fine wire sections are pressed in to the flutes of the broke tap, the collar is slipped down to anchor the wire projections in place and you just back out the broken section. I have broken my share of 6-32 taps. http://www.google.com/imgres?imgurl=http%3A%2F%2Fwww.listoftools.com%2Fimages%2Fusing_a_tap_extractor.png&imgrefurl=http%3A%2F%2Fwww.listoftools.com%2Fbroken_bolts_and_studs%2Fremoving_a_broken_tap_from_a_hole.html&h=226&w=336&tbnid=LOBCrSg7KDZvQM%3A&zoom=1&docid=gh_YBuam-L1FAM&ei=QXR9U8-MJsLgoATGtIGwCw&tbm=isch&client=firefox-a&ved=0CFoQMygCMAI&iact=rc&uact=3&dur=2248&page=1&start=0&ndsp=31

David Rase · « **Reply #15 on:** May 22, 2014, 07:51:15 AM »

Quote from: Dave B on May 22, 2014, 06:45:00 AM

I picked up a tap extractor for a three fluted tap to bail my self out of the exact situation. I have used it on a number of broken taps. I am not sure where it went since we moved. I think mine was for a 8-32 though. They may make one for a 6-32. It works by three fine steel wires held in place by a fluted shaft with a sliding collar. the fine wire sections are pressed in to the flutes of the broke tap, the collar is slipped down to anchor the wire projections in place and you just back out the broken section. I have broken my share of 6-32 taps. http://www.google.com/imgres?imgurl=http%3A%2F%2Fwww.listoftools.com%2Fimages%2Fusing_a_tap_extractor.png&imgrefurl=http%3A%2F%2Fwww.listoftools.com%2Fbroken_bolts_and_studs%2Fremoving_a_broken_tap_from_a_hole.html&h=226&w=336&tbnid=LOBCrSg7KDZvQM%3A&zoom=1&docid=gh_YBuam-L1FAM&ei=QXR9U8-MJsLgoATGtIGwCw&tbm=isch&client=firefox-a&ved=0CFoQMygCMAI&iact=rc&uact=3&dur=2248&page=1&start=0&ndsp=31

Good for you Dave. I have only tried to use a tap extractor a couple of times. And the end results were always less than satisfactory. I finally come to the conclusion that if a tap was tight enough to snap off, then it is probably too tight to be removed with an extractor.
David

eddillon · « **Reply #16 on:** May 22, 2014, 08:49:38 AM »

I have had this happen to me several times. Fordham tool or Dremel with dental drills. Drill all the way through down the center of the broken tap. keep enlarging the hole until you can shatter the tap with a punch. Hole saved.

WKevinD · « **Reply #17 on:** May 22, 2014, 05:18:36 PM »

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Success! I didn't have a small enough/ strong enough punch and the local machine shop didn't have EDM capabilities so we chucked up a .093 end mill hit it with a lot of juice and went through the center, left the threads enough to finish with a tapered 6-32 tap.
Now I'm centered on the web that was just a tad over 5/32" thick.
I really appreciate the helpful advice, I used to have a rifle building buddy and we would bounce around ideas, problems and solutions with, he's gone so this whole forum means alot. Thanks

Stophel · « **Reply #18 on:** May 22, 2014, 11:21:16 PM »

Glad you got it out. I figured what threads you had in the plate already would be fine.

And I've never had luck with the little finger tap extractors either, which is why I didn't even suggest it. I suppose they would probably work with a larger tap, but larger taps rarely break. It's the itty bitty suckers that will break without giving you as much warning!

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Author Topic: Broken Tap- Need Help (Read 7870 times)

docone

eddillon